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Originally Posted by Belfaborac
On the one hand, elcreative is quite right in that Lithium Polymer batteries do this in any and all devices in which they're used. Hence that part of the article is indeed an absolute non-story.
On the other hand, Apple's reply that continuing to charge the battery beyond the point when the indicator shows 100% will harm the battery is either a sign of utter cluelessness on the part of the Apple rep, or an indication that Apple has not implemented an automatic cut-off when 100% charge is really reached.
If the latter is the case, then that's a disaster waiting to happen for anyone who routinely leaves their device charging overnight, which is probably a majority of owners. I can't really believe that Apple would be that stupid, so I'm betting on a dimwitted rep.
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I'm an electronics technician. It's my understanding that all lithium batteries are essentially the same. Each cell in a lithium battery has to charge to 4.2 VDC and then the charger gradually reduces the charge current until it has dropped to a small percentage of the initial charge rate, at which point the battery is considered 100% charged. For most lithium batteries this is typically 2% to 3% although it can be a little more, as in the case of my Viewsonic gTab which is 4% with "fully charged" reported as 96%. The 10% to 20% you and elcreative are suggesting seems a little too high.
Dr. Soneira says that there is something wrong with the battery charge mathematical model on the iPad. He's saying that users will not get the maximum running time that the iPad is capable of delivering.
Dr. Soneira obtained his Ph.D. in Theoretical Physics from Princeton University and his background covers internationally recognized leading edge research in electronics, optics, applied mathematics, theoretical and experimental physics. So I think he is more qualified than you or I or most other members of this forum to speak in this regard.
It's almost my understanding that lithium batteries are smart batteries with a cutoff potential of 4.3VDC to prevent cell damage. Obviously the Apple spokesman is clueless and doesn't know what he is talking about. I'm sure he's taking the proverbial butt-chewing as we speak.